Dehydrogenating hydroxy-and oxocycloaliphatic compounds

ABSTRACT

Alpha-naphthol is obtained by dehydrogenating alpha-tetralol and/or -tetralene in presence of a catalyst comprising finely-divided Ni, Cu, Cr, Fe, Co, Pt, Ir, Pd or Rh deposited on an oxide which contains no acid foci, e.g. kieselguhr, CaO, MgO, CuO, SrO, BaO or ZnO.

Aug. 15,1967 7 RIQG'AC E'II'AL 3,336,399

DEHYDROGENATING HYDROXY-AND OXC-CYQLOALIPHATIC COMPOUNDS Filed Aug. 30, 1963 ROBERT GAC LOUIS ZEPPIERI INVENTORS.

United States Patent 3,336,399 DEHYDROGENATING HYDROXY- AND 0X0- CYCLOALIPHATIC COMPOUNDS Robert Gac, Caluire, and Louis Zeppieri, Oullius, France, assignors to Progil, Paris, France, a corporation of France Filed Aug. 30, 1963, Ser. No. 305,763 Claims priority, application France, Aug. 30, 1962,

4 Claims. ((51. 260621) This invention relates to a process for the manufacture of heavy phenols from corresponding oxygenated cycloaliphatic compounds and, more particularly, to the production of naphthols by the dehydrogenation of alcohols and ketones derived from more or less hydrogenated naphthalene and alpha naphthol, from 1 hydroxy- 1,2,3,4 tetrahydro-naphthalene or 1 oxo -l,2,3,4 tetra hydro-naphthalene.

In the past, various methods have been proposed for the preparation of heavy phenols by the dehydrogenation of the corresponding cycloaliphatic compounds. None of these methods has given complete satisfaction because, for instance, these known methods result in a low rate of transformation and in poor yields. Furthermore, the known processes generally give rise to the formation of considerable quantities of secondary products. For instance, when a catalytic metal is employed in a very active form, such as fresh Raney nickel or platinum sponge, for the dehydrogenation of l-hydroxyor l-oxo- 1,2,3,4 tetrahydro naphthalene, there occurs a simultaneous formation of 5,6,7,8 tetrahydro naphthol 1, which is very diflicult to separate later on from the alphan-aphthol. If the conventional dehydrogenation catalysts (made up of metal oxides) are used, the speed of dehydrogenation is too low and this permits a side reaction to take place to an excessive degree. The same disadvantage is found when using catalysts formed by the deposit of finely divided metal on carriers generally employed for catalytic members, particularly active carbon, clays, and oxides of elements of Groups III to VIII of the Periodic Table, particularly A1 0 TiO SiO and Cr O all compositions containing such oxides. These and other ditficulties experienced with the prior art have been obviated in a novel manner by the present invention.

A principal object of this invention is the provision of a method for dehydrogen-ating hydroxyand oxo-cycloaliphatic compounds and, more particularly, from l-hydroxy 1,2,3,4 tetrahydro naphthalene or 1 oxol,2,3,4 tetrahydro naphthalene of the corresponding naphthols with a high rate of transformation, practically free from tetrahydronaphthol.

With the foregoing and other objects in View, which will appear as the description proceeds, the invention resides in the combination and arrangement of steps and in the details of procedure hereafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed may be made within the scope of what is claimed without departing from the spirit of the invention. The character of the invention, however, may be best understood by reference to one apparatus for carrying out the method, as illustrated by the accompanying drawing, in which:

The single figure is a schematic diagram of apparatus for performing the process of the invention.

In general, the invention consists in the discovery of special catalysts to be used in the dehydrogenation of oxygenated cycloaliphatic compounds for the purpose of obtaining the corresponding heavy phenols. It has been discovered that, in "order for the dehydrogenation of the aliphatic ring to take place selectively, the catalytic mass 3,336,399 Patented Aug. 15, 1967 The new process consists, in the first place, of subjecting oxygenated cycloaliphatic compounds in the liquid state to heating in the presence of a dehydrogenation catalyst made up of one or more finely divided catalytic metals deposited on an oxide support of a basic or entirely neutral character and not containing any composition of an acid character in the free state. Catalytic metals which can be used as part of the catalyst of the invention may be one or more of the metals selected from the group consisting of nickel, copper, iron, cobalt, chromium, platinum, or other metals of the platinum group, such as iridium, palladium, and rhodium. Carriers which can be used with the catalyst include the basic oxides, particularly those of metals of Groups I and II of the Periodic Table, especially calcium oxide, magnesium oxide, copper oxide, strontium oxide, barium oxide, and zirconium oxide. Some oxides, such as silica, may be used, but only in a perfectly neutral form, such as kieselguhr, which does not contain any acid foci.

Catalysts may be prepared in accordance with the invention by using 20 to parts by Weight of the finely divided catalytic metal per 100 parts of carrier. In the preferred embodiment, the catalytic metal makes up 50 to 100 parts per each 100 parts by weight of carrier. A preparation of these catalysts can be carried out in the usual manner. For instance, a mixture of a desired metal oxide with a selected support powder may take place by co-precipitation, by tabletting, or by granulation and reduction in hydrogen, preferably at a temperature equal to or in the vicinty of that at which the catalyst is to be used.

Another important feature of the invention is that the dehydrogenation take place at temperatures which are in the vicinity of the boiling point of the reaction liquid. It is particularly advantageous to work under boiling conditions at atmospheric pressure -or at any pressure from 1 to 5 atmospheres. When the oxygenated cycloaliphatic compound which is to be treated is l oxo 1,2,3,4 tetrahydro naphthalene, the best temperature to use for ob taining alpha-naphthol is in the range from 200 C. to 350 C. The velocity of the reaction and the rate of conversion increases with the temperature and the results are particularly favorable at the boiling point of the reaction mixture, which lies between 256 C. and 290 C. at atmospheric pressure. If the process is carried out at a slightly higher pressure in the range from absolute pressures from 1 to 3 kilograms per centimeter square, the

favorable temperature range would be in the range from 305 C. to 340 C.

In the particular case where the cycloaliphatic compound to be dehydrogenated is 1 hydroxy 1,2,3,4- tetrahydro naphthalene, the temperature at which dehydrogenation should take place is about 240 C., the process of the invention being preferably carried out in a paI- ticular manner; that is to say, by carrying out the reaction in two stages; (1) heating the mixture to boiling under reduced pressure with a contact time in the catalytic space, which is short (just long enough to convert virtually all of the 1 hydroxy 1,-2,3,4 tetrahydro naphthalene to 1 oxo 1,2,3,4 tetrahydro naphthalene, and (2) treatment at a higher temperature as indicated above in relation to 1 oxo 1,2,3,4 tetrahydro naphthalene. It will be understood that this particular embodiment of the invention is applicable not to 1 hydroxy 1,2,3,4 tetrahydro naphthalene only, but also to starting mixtures which contain greater or lesser amounts of this compound. The first stage can advantageously be carried out at a pressure of 400 to 760 millimeters Hg which corresponds to boiling temperatures of about 225 C. to 250 C. The efiiciency of the process is increased by a vigorous agitation of the liquid while in contact with the catalyst. In the case of a fixed bed catalyst this agitation is obtained by a very rapid passage of liquid to be treated through the bed. Another means is by the bubbling of an inert gas (for example, nitrogen) through the liquid in contact with the catalyst. This bubbling should take place at regulated rates within certain limits, particularly 150 to 200 times the volume of the catalytic space per hour.

The process of the invention can be carried out in two different ways: With a fixed catalytic bed, or with catalyst particles in suspension in the reaction medium. When liquids containing principally 1 oxo 1,2,3,4 tetrahydronaphthalene or 1 hydroxy 1,2,3,4 tetra-hydro naphthalene are dehydrogenated to naphthol by passage through a fixed catalytic bed, it is recommended that the catalyst be in the form of granules or particles of a size from 0.5 to 10 millimeters and, preferably, in the range from 2 to millimeters. Larger dimensions lead to a poor utilization of the catalyst, while smaller dimensions increase the loss of charge and risk the formation of gummy residues involving agglomeration of the granules. The linear rates of flow for the reaction liquid through the catalytic bed are preferably from 4 to 100 meters per hour, and, preferably, from to 40 meters per hour, calculated for the theoretically empty apparatus. When the process employs the catalyst in suspension in the reaction liquid, the preferred dimensions of the catalytic granules are less than that used in a fixed bed. They can be in the range from 0.1 to 5 millimeters, but preferably are in the range from 0.1 to 1 millimeter. In fact, below 0.1 millimeter in size separation of the catalyst from the treated liquid after the reaction can be difficult, while granules which are greater than 1 millimeter size are not readily maintained in suspension and lead to a slow rate of dehydrogenation. According to the nature of the liquid and of the catalyst, the suspension can contain 10 to 40 parts by weight of the latter per 100 parts of liquid. However, the preferred proportions are from to parts per 100.

This process can be carried out continuously or discontinuously. In the former case, it is recommended that several reactors be employed in series in order to take into account the rapid decrease in the rate of conversion as a function of time, which is characteristic of the reaction in question. The novel process can be carried out by use of various types of apparatus which allow operation with a fixed bed catalyst or a suspended catalyst.

Referring -now to the accompanying drawing, it can be seen that the apparatus is provided with a flask 11 which serves for the intermediate storage of liquid obtained by a dehydrogenation which takes place in a reactor 14 of the starting material obtained from a reservoir 15. A supply pump 16 causes the liquid to pass from the reservoir 15 into the bed of catalyst in the reactor 14. At the same time, the bed receives the treated liquid from the flask 11 by way of a circulation pump 12. The liquid passes through a preheater 13 and arrives at a catalytic bed at the desired temperature, for instance, 250 C. The reactor 14 is provided with a heater 28 which permits the catalyst bed in the reactor 14 to be preheated. At its upper part, the reactor is provided with an enlargement 25 provided with an overflow pipe 26 which leads back to the flask 11. The top of the enlargement 25 is provided with a column 17 through which the vapors evolved by the reaction pass and, eventually, reach a condenser 18. At the bottom of the condenser 18 a separator 20 is provided in which water recovered separates out and is removed through the pipe 21. The hydrogen escapes through a vent 19 at the top of the separator.

The decanted liquid from the separator 20 returns to the flask 11 through a pipe 22. A vent 24 at the top of the flask 11 is provided with a cooler for avoiding the escape of naphtholic vapors into the atmosphere. Withdrawal of the finished product is made by way of a takeoff valve 23 and a valve 27 regulates the flow of liquid from the pump 16 to the reactor 14. The reaction can also be carried out with a single passage of the reaction mixture through a tubular apparatus of sufficient length but which is divided into several sections for eliminating the hydrogen produced in each section. However, in order to achieve high rates of flow of liquid, in accordance with the invention, it is generally more advantageous to recirculate the reaction mass in a closed circuit through the catalyst in order to obtain the desired rate of conversion. The apparatus shown in the drawing is particularly suitable for this type of operation. A predetermined volume of the primary material is withdrawn from the reservoir 15 and the pump 16 forces it into the reactor 14. The valve 27 is then closed and operation takes place using the circulation pump 12. The liquid circulates around the various circuits, while the hydrogen formed in the reactor 14 is released through the pipe 19. When the flask 11 contains the desired naphthol (or other heavy phenol) content, the material is withdrawn through the valve 23 and a new charge of starting material from the reservoir 15 is introduced into the apparatus.

In the examples which follow, two types of catalysts are used, indicated by the letters A and B.

CATALYST A In the examples, A represents a catalyst prepared in the following manner:

1 part by weight of cupric oxide (CuO) was mixed with 2 parts by weight of zinc oxide (ZnO) and made into tablets in the usual manner. Two kinds of particles were prepared in this manner: (1) Tablets in the form of cylinders which are 3 millimeters long and 3 millimeters in diameter, and (2) Granules of selected sizes from 0.2 to 0.5 millimeter; 0.5 to 1 millimeter; 1 to 2 millimeters; and 2 to 5 millimeters; formed by grinding and screening the tablets. In both cases, the catalyst is reduced in hydrogen between C. and 275 C. to effect complete transformation of the CuO into finely divided metallic copper.

CATALYST B The catalyst designated B in certain of the following examples is made up of metal deposited on kieselguhr, in the well-known manner. The catalyst contains 50% by weight of nickel and includes no acid foci. Kieselguhr is a mineral of completely neutral SiO This catalyst was made in two forms similar to those in catalyst A, that is to say, (1) cylindrical pastilles of 5 x 5 millimeters, and (2) four series of granules of pre-determined size in the range from 0.2 to 0.5 millimeter; 0.5 to 1 millimeter; 1 to 2 millimeters; and 2 to 5 millimeters; after reduction of the nickel oxide to metallic nickel is was superficially re-oxidized in order to stabilize the catalyst.

Example I In an apparatus of the kind shown in the accompanying drawing, the reactor 14 had an internal diameter of T8 square centimeters and was filled with 1,000 grams of catalyst A in rods 3 millimeters long and 3 millimeters in diameter and preheated by means of the heater 28 to 250 C. 1700 grams of tetralone were preheated to 250 C. in the flask 11 and then circulated at the rate of 7.5 litres per hour, namely, at a linear velocity of 10 meters per hour through the catalyst bed. The composition of the mixture obtained as a function of time is given in Table I.

Examples II and III The operation proceeded in the same manner as Example I, but at temperatures of 230 C. and 200 C., re-

spectively. The results are also given in Table I.

6 Example VIII TABLE I Composition Product (percent by weight) 1 Temp. Time Example C.) (hours) By-products Alpha- Tetrahydronaphthol naphthol Light Heavy 2 34. 6 0. 1 6 3. 0 3 40. 0 0. l 8 3. 9 4 41. 2 0. 1 9 5. 2 6 41. 9 0. 1 13 7. 3 2 230 1 20. 4 0 9 9. 4 2 28. 4 0 15. 0 12. 7 3 30. 2 0. 1 15. 5 13. 4 4 36. 0 0. 1 15. 5 13. 6 6 38. 5 0. 1 16. 0 14. 7 3 200 1 ll. 6 0 2 13. 6 0 3 15. 1 0 6 19. 3 0 10 22. 1 0

Example IV and withdrawal were carried on cont1nuously at the rate In the same apparatus as that shown in the drawings, 1,000 grams of catalyst B was introduced, as described in Example II, in the form of rods of 5 millimeters diameter and 5 millimeters long. The operation proceeded with 2,000 grams of 'tetralone at 250 C. with circulation at the rate of 10 meters per hour. The results are tabulated in Table II below.

Example V The operation took place exactly as in Example IV but at boiling temperature, namely 258 to 280 C. The

results are shown in Table II.

Example VI The operation took place exactly as in Example V but the linear velocity of the liquid over the catalyst was increased to 24 meters per hour. The results are shown in Table II.

Exam ple VII of 1,700 gallons per hour. The composition of the mixture withdrawn was stabilized at 28.2% alpha-naphthol, 8% light ends and 5% heavy ends.

Example IX The process took place in the same manner as in Example VI using 1,000 grams of catalyst B. The mixture was at its boiling point but the charge was made up of 2,000 grams of mixture of 76% l-oxo-l,2,3,4-tetrahydronaphthalene and 24% 1 hydroxy-1,2,3,4 tetrahydronaphthalene. After one-half hour the rate of conversion was 100% for l-hydroxy-1,2,3,4-tetrahydro-naphthalene and 45% for l-oxo-l,2,3,4-tetrahydro-naphthalene. The mixture obtained contained 44% of alpha-naphthol.

Example X Two forms of apparatus analogous to those in the drawing were mounted in series. The first was charged with 1,000 grams of catalyst A and an absolute pressure of 600 mm. Hg was maintained. The second was charged with 1,000 grams of catalyst B at atmospheric pressure. The assembly was supplied continuously with a mixture containing 62% 1-oxo-1,2,3,4 tetrahydro-naphthalene, and 38% 1-hydroxy-1,2,3,4 tetrahydro-naphthalene at the rate of 2,000 grams per hour. The two units were maintained at the boiling point of the liquid mixture. At the outlet from the first unit a mixture containing 11.5% of alpha-naphthol, 6.2% light ends, 3.7% heavy ends, and only 0.3% of l-hydroxy-1,2,3,4 tetrahydro- TABLE II Composition of Product; (percent by weight) Temp. Time Example 0.) (hours) By-products Alpha- Tetrahydronaphthol alpha-naphthol Light Heavy naphthalene. At the outlet of the second reactor, the final mixture contained 57.2% alpha-naphthol, 11.5% recoverable light ends (l,2,3,4 tetrahydro-naphthalene), 6.7% of tar, and 1.4% of tetrahydro-naphthol.

the yield in utilizable products with respect to the l-oxo- 1,2,3,4-tetrahydro-naphthalene varied between 97% and 92.5% in accordance with the duration of the reaction.

While it will be apparent that the illustrated embodi E l XI ments of our invention herein disclosed are well calcummp e lated to adequately fulfill the objects and advantages pri- In a reactor provided with mechanical stirrer and a marily stated, it is to be understood that the invention is reflux condenser serving as a hydrogen outlet, 1,000 grams susceptible to variation, modification and change within of 1-oxo-1,2,3,4-tetrahydro-naphthalene were introduced the spirit and scope of the sub-joined claims. at 250 C. and 250 grams of catalyst A in granules of The invention having been thus described, what is 0.5 to 1 mm., were added. After five hours of reaction, claimed as new and desired to secure by Letters Patent the rate of conversion was 70.1% and the wield of alphai naphthol was 73% with respect to the 1 oXo-1,2, 1. In a process for the manufacture of alpha-naphthol tetrahydro-naphthalene consumed. Also, the major part by dehydrogenation of at least one of the compounds of the by-products were recoverable and constituted by l-hydroxy 1,2,3,4 tetrahydro-naphthalene and l-oxonaphthalene and tetraline. 1,2,3,4-tetrahydro-naphthalene, with a metallic dehydro- Example X genation catalyst constituted by at least one divided metal selected from the groups consisting of nickel, copper, 01161115011 Was analogous to Example XIII but at the iron, cobalt, chromium, platinum, iridium, palladium, and boiling Point, namely Q and with rhodium, deposited on an inert carrier, the improvement chanical agitation using 250 grams of catalyst A in g which consists in heating a feed material consisting of ules of 1 to 2 mm. After five hours the rate of conversion at l t one f id compounds in the liquid state, in the WaS 835% and the yield of alpha-naphthol Was presence of said catalyst, said inert carrier being a metal- Example XIII lic oxide selected from the group consisting of basic Th d t th metallic oxides and neutral metallic oxides, containing E e process was (fame m e m manner as no compound of acidic character in the free state said xample XII but with catalyst A used in granules of h b t t b t C d 350 0.2 to 0.5 mm. After five hours the conversion rate was ea mg i a a tempera ure 8 ween an 865% andtheyieldOfalpha naphthO1-/8 5% C.; removing the hydrogen formed as a result of said heating and separately recovering the alpha-naphthol pro- Examples XIV through XVII duced by Said heating The process wa arried out i the same manner as 2. A process as recited in claim 1, wherein said carrier Examples XII and XIII but with 250 grams of catalyst is selected from the class consisting of MgO, CaO, CuO, B. Table III shows the results obtained. ZnO, SrO, and BaO.

TABLE III Ex. Catalyst B Time 0.5 hour 1 hour 1.5 hours 2 hours Dimensions oi granules; 14-. 5mm Conversion.-. 54.3 73.8 Yield 77. 5 76. 1 15 1-2mm Conversion... 60 79.3 84.3 Yield 70.5 73.5 16- 0.2-0.5 mm 80.9 35. a

Example XVIII 3. A process in accordance with claim 1, wherein the The Operation was carried out in the same manner as catalyst is nickel and the carrier completely neutral sili- Example XVI but replacing the 1-oXo-1,2,3,4-tetrahydro- 2 naphthalene with a mixture of 24% 1-hydroxy-1,2,3,4- d process .reclted 1n.cla1.m.1wherem saldcatilyst tetrahydro-naphthalene and 76% 1-oXo-1,2,3,4 tetrag on i d W." 15 m the form of parades hydro-naphthalene. After two hours of reaction, the rate an 15 Suspende m the hquld compounds to be dehydro' of conversion reached 100% for 1-hydroxy-1,2,3,4-tetragenated' hydro-naphthalene and 69% for 1-oXo-1,2,3,4-tetrahydro- References cued naphthalene and the yield of alpha-naphthol was 67%. UNITED STATES TENTS The total yield of the usable product was 21.5%. 2,321 551 6/1943 Loder Table III 'gIVFS the rates of conversion in yields of 2,503,641 4 1950 Taylor et alpha-naphthol in percent by weight with respect to the 1-oxo-1,2,3,4 tetrahydro-naphthalene consumed. Also, the greater part of the by-products was recoverable and LEON ZITVER, Primary Examiner.

D. M. HELPER, H. ROBERTS, Assistant Examiners. 

1. IN A PROCESS FOR THE MANUFACTURE OF ALPHA-NAPHTHOL BY DEHYDROGENATION OF AT LEAST ONE OF THE COMPOUNDS 1-HYDROXY - 1,2,3,4 - TETRAHYDRO-NAPHTHALENE AND 1-OXO1,2,3,4-TETRAHYDRO-NAPHTHALENE, WITH A MATELLIC DEHYDROGENATIONCATALYST CONSTITUTED BY AT LEAST ONE DIVIDED METAL SELECTED FROM THE GROUPS CONSISTING OF NICKEL, COPPER, IRON, COBALT, CHROMIUM, PLATINUM, IRIDIUM, PALLADIUM, AND RHODIUM, DEPOSITED ON AN INERT CARRIER, THE IMPROVEMENT WHICH CONSISTS IN HEATING A FEED MATERIAL CONSISTING OF AT LEAST ONE OF SAID COMPOUNDS IN THE LIQUID STATE, IN THE PRESENCE OF SAID CATALYST, SAID INERT CARRIER BEING A METALLIC OXIDE SELECTED FROM THE GROUP CONSISTING OF BASIC METALLIC OXIDES AND NEUTRAL METALLIC OXIDES, CONTAINING NO COMPOUND OF ACIDIC CHARACTER IN THE FREE STATE SAID HEATING BEING AT A TEMPERATURE BETWEEN 200*C. AND 350* C.; REMOVING THE HYDROGEN FORMED AS A RESULT OF SAID HEATING AND SEPARATELY RECOVERING THE ALPHA-NAPHTHOL PRODUCED BY SAID HEATING. 